Manufacture of artificial silk



Patented July 26, 1938 MANUFACTURE OF ARTIFICIAL SILK James Joseph Polak, Arnhem, and Johannes G. Weeldenburg, Ede, Netherlands, assignors to American Enka Corporation, Enka, N. 0., a corporation of Delaware No Drawing. Application January 25, 1937, Se-

rial No. 122,323. In Germany February 15,

45 Claims.

This application is a-continuation in part of our application Serial Number.5l,332, filed November 23, 1935.

The present invention has to do with a new and novel method for use in the manufacture of yarn or other materials of artificial origin and the products thereof.

More specifically, the present invention concerns a novel process for maintaining ideal spinning conditions in the manufacture of yarn of artificial origin.

In the manufacture of artificial filaments, threads, yarns, ribbons and the like, a cellulosic solution is prepared and expressed or extruded through minute openings into a coagulating or precipitating medium. This medium is usually either liquid or gaseous.

In preparing the cellulosic spinning solutions referred to in the specific examples of the present case, cellulose is treated with caustic to form alkali cellulose, which, with carbon disulphide, produces a xanthate. This, in solution, produces a viscose spinning solution.

In the present specification we shall describe our invention with respect to a viscose process, but it must be understood that the underlying principle is broad, and that we do not wish to be limited to any specific, minute application of our concept.

In the commercial production of artificial yarn and analogous products, it is economically necessary, if possible, to provide for uninterrupted spinning of all filaments. Ordinarily the objections arising which occasion interruptions to the spinning or extruding step, are caused by the contamination of the spinnerets themselves. This fault can, we believe, be traced to the presence of suspensions, reaction products, and impurities of various kinds in the viscose solution or the spinning bath which tend to agglomerate or deposit on the spinneret and partially or entirely block the small orifices therein. These materials might include, among others, precipitated cellulose, sulphur deposits, particles of resin, secondary reaction products, and the like.

We have noted this phenomenon more especially when acid spinning baths are employed and particularly where zinc sulphate is present tend to form at the obstructions, either in or around the orifices of the spinneret, which, when filaments are extruded there through, might cause a temporary interruption of the spinning of a filament at the orifice afiected, thus occasioning a tearing of the filament. These faults incur additional expense due to the manipulation necessary to change spinnerets, the loss accruing from stopped production, and the increase in lower quality yarns, for which yarns a lower price, only, may be asked.

The partial or total clogging of orifices is noticeable with the usual metal spinnerets, which spinnerets are made from gold, gold-palladium, gold-platinum, tantalum, et cetera. Furthermore, spinnerets are manufactured from precious and semi-precious stones, such as natural ruby, synthetic ruby, et cetera. Our improved procedures are applicable in the use of these various types of spinnerets. The economic advantage oi. finding asimple, inexpensive method for keeping spinnerets operative during spinning is therefore apparent. As will be subsequently pointed out, other improved spinning conditions will be realized when following our procedures wherein we provide a solution for these problems in our present inventive concept.

Briefly, we have discovered that if certain cation-active compounds are included either in the spinning bath and/or the spinning solution, the clogging of spinneret openings is considerably diminished or even prevented, and a very remarkable improvement of the spinning process per so will result. More specifically, cation-active aliphatic, carbocyclic or heterocyclic substances have been employed with signal success in actual practice. By stating that certain" cation-active compounds are employed it is intended to mean that only those cation-active compounds are suitable which are sufliciently soluble and substantially stable in the spinning bath or the celluloslc solution or in both. Cation-active compounds are surface-active compounds which carry in the cation the group or radical which is responsible for the surface activity. In contradistinction anion-active compounds are surfaceactive compounds which carry in the anion the group which is responsible for the surface activity. Such groups responsible for surface activity in this specification are called surface-active groups. Other groups or ions which are inert in this respect will be called surface-inactive or innocuous.

Surface activity as used herein is the property,

among other physico-chemical characteristics, of reducing surface or interfacial tension.

As an additional advantage we have found that when such cation-active substances are added to the viscose spinning bath, either by direct addition or as a result of addition to the viscose solution,-.the colloidal sulphur therein tends to agglomerate, and is easily filtered off if desired. Together with the removal of the sulphur thus eifected, which in itself represents an ,impurity, other dissolved or suspended particles contaminating the spinning bath may be also precipitated and removed.

Surface activity depends upon the presence of one or more groups or radicals with long or extended chain-like structures which include extended aliphatic, carbocyclic and heterocyclic chains or combinations thereof. Compounds which contain a surface-active group show a tendency, according to the experiments and theory of Langmuir, to accumulate in the surface or interface of the solution and to assume an oriented position in which all of the extended chains lie parallel. Naturally, these substances can show this property only'in so far as they are dissolved. When the molecules ionize, the surface activity may be induced by either the cation or the anion. This depends upon the position of the extended chain when the molecule ionizes.

If, when the molecule ionizes, the extended chain remains with that part of the molecule bearing the positive charge, then it is said to be cation active; whereas, on the other hand, if the long chaingemains with that part of the molecule which bears a negative charge, it is said to be anion-active. Most of the usual surface-active substances are anion-active, with which substances the present invention is not concerned.

The compounds as exemplified below are 11- lustrative of compounds which may be used in accordance with our invention. A general structural formula for a compound of this type may be expressed as RI X']A. -s.. c

In this structure represents the cation and A represents the anion. X represents a polyvalent atom, or a radical containing such an atom, capable of being linked to a negative atom or radical and at the same time to one or more other atoms or radicals. The letter 1/ indicates the valence of the atom or radical X. The invention also contemplates the presence of more than one atom symbolized by X in the cation. In this event one or more of the X atoms may be linked to surface-active groups and to surfaceinactive atoms or radicals as described herein. 3 designates the radical or radicals inducing cation-activity, which are linked directly to the polyvalent atom of X. S may include one or more of the same or different aliphatic, carbocyclic and heterocyclic radicals and the letter m is a positive whole number indicating the total number of such radicals. The radical or radicals S should be such that when linked to X it or they will provide, in an ionizing solvent, a surfaceactive cation. B. may be hydrogen and/or one or more of the same or difierent aliphatic, carbocyclic or heterocyclic radical or radicals which are distinguished from those of B in that they do not induce surface-activity into the cation. The

letter 11. is a positive whole number or zero and indicates the total number of such radicals and/or hydrogen atoms. This letter 1: also'in- 5 dicates the number of valences of the atom of x which remain available to be saturated by ining the valence of the anion. The letter C outside 15 of the bracket is a whole positive number indicating the number of cations linked to the anion.

In the examples given herein C- equals c-and the sum of n and m. equals 11-4.

It is to be understood that all compounds of the above named general structure have the character of bases (wherein A would be a hydroxyl radical) or their salts, including acid salts. The more important cation-active compounds which may be employed in accordance with the present invention are the bases or their salts, such as may be derived from pentavalent nitrogen, and further the sulphonium, phosphonium and arsonium, etc. bases and their salts. The polyvalent atom of x in the foregoing formula is in these compounds nitrogen, sulphur, phosphorus and arsenic, etc., respectively. The quaternary ammonium compounds are examples of compounds containing such an atom, nitrogen being the polyvalent atom. Of these, the pyridonium or'pyridinium compounds are examples of compounds in which the polyvalent atom, nitrogen, is contained in a radical, the radical being the pyridine ring (CtHsN) having a valence of two. Other radicals containing the polyvalent atom may, of course, be used in place of the pyridine ring.

l'n'the bases or their salts illustrated by the above formula the innocuous anion symbolized by A is the hydroxide, chloride, sulphate, bromide, iodide, acetate, etc. The groups inducing cation activity symbolized by Sm comprise extended chain-like structures, such as aliphatic hydrocarbon chains having six or more carbon atoms therein. Also, the extended chain-like structures may be composed of two or more benzene 'nuclei or other cyclic radicals, either combined directly or, for example, through a carbon or nitrogen or other linkages, with or without aliphatic chains substituted for the hydrogen in rings.

Referring now in detail to specific examples of suitable compounds, bases derived from nitro-- gen and their salts, for instance, certain pyridinium and other quaternary ammonium compounds, have been found to be particularly suitable. The former compounds may include pyridinium bases or salts having linked thereto extended aliphatic chains, containing, for example, sixor more carbon atoms and preferably 12 to 20' carbon atoms. Specifically, dodecyl, hexadecyl, octadecyl, or even a lower carbon chain such as decyl may be linked to the nitrogen atom in the bases or salts of pyridinium such as pyridinium hydroxide, pyridinium sulphate or bisulphate and pyridinium bromide. Use may also be made of 'replacement'or substitute compounds such as the analogous substitution products of pyridine known as picoline (C5H4N(CH3)), and quinoline (Cali-1N), etc. and also compounds such a,1ss,os1

radicals were replaced by radicals capable of u as piperidin e, acrid ine. cinnoiine and naph hyridin and their derivatives.

An example of such. compounds is the bisul phate 'or acid sulphate of dodecyl-pyridinium, having the structure: g

. a UnHn hsoi In this compound the letter X represents the pyridine radical {N including the polyvalent atom nitrogen and having a valence y of 2; Bis the dodecyl radical CzaHzs connected directly to the polyvalent atom (nitrogen) of X, the letter m being 1. The innocuous anion A is the bisulphate radical (H504) connected directly to the polyvalent atom of X. The valence of A is l, ,and the letter 0 just outside the bracket is 1. In this compound the value of n is 0, so there would be no atom or radical R.

If the other hydrogen of the bisulphate were replaced by a second dodecyl pyridinium group the innocuous anion (804) would have a valence of 2 and the letter 0 outside .the bracket would become 2, indicating two dodecylpyridinium 35 groups satisfying the two valences of the anion.

In the bases or salts of picoline and quinoline the (CsI-I4N(CH3)) and the (Coll-1N) groups, respectively, would be the radical X containing the polyvalent atom, nitrogen.

In the other quaternary ammonium compounds the same innocuous anions and surface-active groups may be linked to the pentavalent nitrogen atom as are employed with the pyridinium compounds. In this case X represents the atom nitrogen, having flve valences. The three valences which are saturated in the pyridinium compounds 'by (CHM are now saturated by alkyl, aryl or other carbocyclic or heterocyclic groups and/or hydrogen atoms. For instance, three methyl groups may be used to form trimethyl dodecyl ammonium bromide. The following is' the structural formula of such a compound:

(CHs) \Br CnH In this case It would be the (CH3) radical, the letter 1: being 3, and A would be the bromine atom.

If two butyl radicals are substituted for two of the methyl radicals in the above compound, methyldibutyldodecyl ammonium bromide would be formed. In this event the R would represent different radicals (CH: and C4Ho) the total number of which would be 3. 3

Also the compound might contain more than one dodecyl radical or-other radical capable of inducing the surface-activity of the cation. For example, one or more of the methyl radicals in the above compound might be replaced by a dodecyl radical, in which event theletter m would be 2 or more, depending upon how many methyl radicals were so replaced, and the letter u would be correspondingly decreased. If all the methyl the inducing the surface activity of the cation, the 4 letter 11 would, of course, become zero.

- As previously indicated the radicals capable of inducing the surface-activity of the cation may include aromatic or other carbocyclic or heterocyclic radicals. The following compounds are examples of compounds containing such radicals including benzene nuclei in the surface-active groups in the' cation: toluene azophenyl-trimethyl ammonium iodide, benzene azophenyl trimethyl,

ammonium iodide, diphenyl azophenyl trimethyl ammonium methyl sulphate, isophopyl naphthyl trimethyl ammonium iodide. In such compounds of the cation.

Where the innocuous anion is divalent, as in the case of a sulphate in which both hydrogens are replaced by surface-active cations, a compound of the following type may be used:

OIHI

di (dodecyl-triethyl ammonium) sulphate.

By the same token that the cation-active pyridonium and other ammonium compounds are suitable in connection with the present invention, sulphonium, phosphonium and arsonium bases and their salts may also be used. 01' course, in order for this to be true, the sulphur, phosphorus or arsenic must have linked directly thereto, an innocuous anion and at least one group inducing surface activity in the cation. It is apparent that the sulphur being tetravalent, as distinguished from the pentavalent phosphorus and arsenic will have less valences to' be saturated than in the case of phosphorus, arsenic and nitrogen. For example, a sulphonium compound such as diethyl dodecyl sulphonium hydroxide would correspond to triethyl dodecyl phosphonium hydroxide, either of which might be used. As further examples of these types of compounds, trimethyl dodecyl phosphonium hydroxide and dipropyl dodecyl sulphonium bromide may be employed. It is also within the scope of our invention to use compounds in which the polyvalent atom of X is divalent or trivalent. The prerequisites of such an element must be that they will combine with an innocuous anion and a group inducing surface-activity in the cation.

The following are a number of compounds that may be used in accordance with our invention:

Octyl pyridinium iodide, dodecyl pyridinium bromide, hexadecyl pyridinium. iodide, octadecyl pyridinium-bromide, dodecyl pyridinium iodide, dodecyl pyridinium chloride, dodecyl-triethyl am- 4 monium iodide, octyl-triethyl ammonium iodide, decyl-triethyl ammonium iodide, dodecyl-triethyl ammonium iodide, hexadecyl-triethyl ammonium iodide, toluene azophenyl-trimethyl ammonium iodide, benzene azophenyl-trimethyl ammonium iodide, diphenyl-azophenyl-trimethyl ammonium methylsulphate, isopropyl naphthyl trimethyl ammonium iodide, diethyl-dodecyl sulphonium hydroxide, triethyl-dodecyl phosphonium hydroxide, trimethyl-dodecyl'phosphonium iodide, trimethyl-dodecyl phosphonium bromide, diphopyldodecyl sulphonium bromide, etc.

Also unsaturated as well as saturated aliphatic radicals may be used as the radical inducing surface-activity in the cation (8) or as the inactive radical (B).

As pointed out above, the cation-active compounds may be added directly to the viscose spinning baths, or may be mixed with the viscose solution prior to extrusion into the baths, or they may be employed simultaneously in both the bath and spinning solution. It is of course necessary to select a cation-active compound which is not adversely affected by the acid of the bath and is substantially stable when used therein, and/or one that is stable in viscose when used therein. Compounds which 7 are sufficiently soluble in dilute caustic soda or viscose to go into molecular solution in the viscose itself are particularly adapted to be added to the spinning solution. The tetraalkylammonium bases and salts and aryltrialkylammonium bases and salts are especially suited for this purpose because of v their greater stability toward the alkali of the viscose. When the compound is added to the spinning bath it is preferred to use a compound that goes into molecular solution in the spinning bath.

We herewith give three specific examples in order to more clearly disclose the present process:

Example 1.0rdinary viscose solution is made a up, and spun or extruded through fine orifices in precious metal spinnerets into a well-known acid spinning bath, containing sulphuric acid, sodium sulphate, ammonium sulphate, and a small quantity of zinc sulphate. Such a bath, although widely known and used, is ordinarily troublesome since spinning difficulties due to the contaminated spinnerets, are common. We add to the bath, however, a small quantity (0.04 per cent by weight) of dodecyl pyridinium bisulphate. A

desirable range of this material is between one thousandth per cent and eight hundredth per cent. Such a small addition eliminates most of the spinning irregularities and diiliculties, and enables a much longer spinning time free from the noted interruptions than has been heretofore possible.

Example 2.-An ordinary viscose solution is extruded through gold-palladium spinnerets into a spinning bath of the type mentioned in Example 1, but which contains a relatively larger amount of zinc sulphate, for example, five per cent of this salt. Ordinarily, under these conditions, the spinnerets become sufflciently contaminated in a few hours to deleteriously affect spinning, as pointed out above. However, if 0.1 per cent by weight of dodecyl triethyl ammonium iodide is first added to the viscose solution, the tendency to clog the holes of the spinnerets will be greatly reduced.

Example 3.An ordinary viscose solution is spun through gold-palladium spinnerets into a spinning bath containing, for example, in addition to the usual bath ingredients 5% zinc sulphate; under these conditions the holes of the spinnerets will become contaminated within a few hours. If, however, 0.05% toluene azophenyltrimethyl ammoniiun iodide is added to the viscose solution, there will be much less clogging of the spinneret holes.

We believe it remarkable that such small and relatively inexpensive amounts of substances may be employed, and still give such good results.

It must be understood that if the addition is I made to the spinning bath rather than to the spinning solution, as set forth in Example 1, small further additions are necessary from time to time to replenish the compound lost or removed during the spinning operation. By yam we intend to cover filaments, threads, ribbons, foils, or other products usually produced by extrusion or spinning of a so-called celiulosic solution of artificial origin.

Having now set forth our invention as required by the patent statutes, we desire to be limited only to the extent set forth in the following claims.

We claim:

1. In the manufacture of cellulosic materials of artificial origin formed from a celiulosic solution that would normally incur the contamination of spinneret orifices, the step which comprises extruding such a cellulosic solution through spinneret orifices in the presence of a dissolved cation-active substance that is substantially stable under spinning conditions.

2. In the manufacture of cellulosic materials of artificial origin, the step of extruding an aqueous celiulosic solution through orifices in the presence of a very small proportion of a dissolved compound supplying surface-active cations and innocuous anions, said compound being stable under spinning conditions.

3. In the manufacture of cellulosic materials of artificial origin formed from a celiulosic solution that would normally incur the contamination of spinneretorifices, the step which comprises extruding such a celiulosic solution into a spinning bath containing dissolved therein a compound supplying surface-active cations and innocuous anions.

4. In the manufacture of cellulosic materials of artificial origin, the step of extruding a viscose solution into an acid spinning bath containing dissolved therein a compound capable of supplying surface-active cations and innocuous anions.

5. In the manufacture of cellulosic materials of artificial origin, the step of extruding a viscose solution into an acid spinning bath containing zinc sulphate and having dissolved therein a compound capable of supplying surfaceactive cations and innocuousanions.

6. In the manufacture of yarn of artificial origin from a celiulosic solution that would normally incur the contamination of spinneret orianion, said substance being stable under spinning cc editions.

8. In the manufacture of viscose yarn wherein a viscose solution is extruded through minute or fices into an acid precipitating bath to form 111 unents and the like therefrom, the step which therefrom, the step which comprises spinning the filaments in the presence of a dissolved, stable, cation-active, tetra-substituted ammonium compound having at least one chain containing at least six carbon atoms and having an innocuous anion.

10. In the manufacture of viscose yam wherein a viscose solution is extruded through minute: orifices into an acid precipitating bath to form filaments and the like therefrom, the step which containing at least six carbon atoms.

comprises spinning the viscose filaments in the presence of a dissolved, stable" cation-active, tetra-alkyl ammonium halide. Y

11. In the manufacture of viscose yarriiwherein a viscose solution is extruded througlyminute orifices into an acid precipi t Ia ting; bath:.;to' form filaments and the like therefrom, the step which comprises spinning fthey'viscose filaments -in the I presence of a dissolve, 'stabler cation-active,

tetra-alkylammonium Iii-pound; having' an; in- I nocuous anion.

12. 'In the manufacture of' viscose yarn wherein a viscose solutioi'i'is textifl'lddthrou hi presence of a dissolved, tetra-alkylammonium compo one chain containing at. least ix arb' and having an innocuousamb 13. In the manufacture II I yarn; herein a viscose solution is extruded through" minute orifices into an acid precipitating bath to. form filaments and the like therefrom, the step which comprises spinning the "viscose filaments in the presence of a dissolved, stable, cation-active substituted pyridinium compound having an innocuous anion.-

14. In the manufacture of viscose yarn where-. in a viscose solution is extruded through minute orifices into an acid precipitating bath to form filaments and the like therefrom, the step which comprises spinning the viscose filaments in the presence of a dissolved, stable, cation-active, subfilaments and the like therefrom, the step which comprises spinning the viscose filaments inthe presence of a dissolved, stable, cation-active alkyl substituted pyridinium halide. 7 16. In the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acidprecipitatingbath to form filaments and the like therefrom, the step which comprises spinning the viscose filaments in the presence of a dissolved, stable, cation-active,

alkyl substituted pyridinium compound having an innocuous anions 1 17. In the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acid precipitating bath to form filaments and the like therefrom, the step which comprises spinning the viscose filaments in the presence of a dissolved, stable, cation-active pyridinium salt having an innocuous anion.

18. In the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acid precipitating bath to form filaments and the like therefrom, the step hich comprises spinning the viscose filaments n the presence of a dissolved, stable, cation-active, tetra-alkylammonium salt having an innocuous anion.

19. In the manufacture of viscose yarn where- 'in a viscose solution is extruded through minute orifices into an acid precipitating bath to form filaments and the like therefrom, the step which comprises spinning the viscose filaments in the presence of a dissolved, stable, cation-active tetra-=alkylammonium iodide having a chain 20. In the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acid precipitating bath to form -precipitating bath containing about 0.04% by weight of a dissolved, stable, cation-active substance.

22. A cellulosic solution that would normally incur the contamination of spinneret orifices when used in the production of yarn including a very small proportion of a dissolved cation-active substance that is stable in the cellulosic solution.

23. A viscose solution for use in the production of yarn including a very small proportion of a dissolved cation-active substance that is stable in the viscose solution.

f 24. A viscose solution containing a dissolved cation-active substance comprising a tetra-alkylammonium compound with at least one chain containing at least six carbon atoms and having an innocuous anion.

25. A viscose solution containing a dissolved cation-active substance comprising dodecyl triethylammonium iodide.

26. An acid spinning bath, for coagulating cellulosic filaments therein, containing a coagulating agent and a very small proportion of a dissolved, stable, 'cation-active substance having an innocuous anion.

'27., A spinning bath, for coagulating cellulosic filaments therein, containing a coagulating agent and dodecyl pyridinium chloride. I 28. A viscose spinning bath, for coagulating *viscose filaments therein, containing a coagulating; agent and a dissolved cation-active substance comprising a salt of a pyridinium base with at least one chain having at least six carbon atoms, said salt having an innocuous anion.

29. A viscose bath containing a coagulating agent and dodecyl pyridinium bisulphate.

,.001 to .08% by weight of dodecyl pyridinium bisulphate is added to the spinning bath.

34. A'method as defined in claim 3 in which about .04% by weight of dodecyl pyridinium bigsulphate is maintained in the spinning bath.

35. A method as defined in claim 7 in which dodecyl triethyl ammonium iodide is added to the viscose solution before extruding.

36. A method as defined in' claim '7 in which about 0.1 by weight of dodecyl triethyl ammonium iodide is added to the viscose solution before extruding.

3'7. An acid spinning bath for coagulating viscose filaments, said bath containing sulphuric I acid, sodium sulphate, zinc sulphate and a. dissolved cation-active compound that is substantially stable under spinning conditions.

38. In the manufacture of viscose yarn, the step which comprises extruding a viscose solution having dissolved therein a cation-active tetra alkyl ammonium iodide into an acid precipitating bath to form filaments and the like therefrom.

39. In the manufacture of cellulosic materials of artificial origin, the step of extruding a viscose solution into an acid spinning bath containing dissolved therein a cationactive alkyl substituted pyridinium halide.

40.'In the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acid 'precipitating bath to form presence of'a dissolved cation-active onium compound having an innocuous anion, which compound is stable under spinning conditions.

41. A method as defined in claim 40 in which the onium compound is employed in a range from 0.001% to 0.1%.

42. In'the manufacture of viscose yarn wherein a viscose solution is extruded through minute orifices into an acid precipitating bath to form filaments and the like therefrom, the step which comprises spinning the viscose filaments in the presence of a dissolved cation-active onium com pound of nitrogen having an'innocuous anion, which compound is stable under spinning conditions.

43. In the manufacture of viscose yarn, the step which comprises extruding a viscose solution, having dissolved therein a cation-active onium compound in a range of from 0.05% to 0.1%, into an acid precipitating bath to form filaments and the like therefrom.

44. An acid spinning bath, for coagulating viscose filaments therein, containing a coagulating agent and a small amount of a dissolved cationactive "onium compound having an innocuous anion.

45. An acid spinning bath as defined in claim 44 which further includes zinc sulphate.

JAMES JOSEPH POLAK. JOHANNES G. WEELDENBURG. 

